Piston seal



14, 1940 l c. sAuzEDDE n v 2,200,305

PlsToN ASEAL l Filed Oct. 30. 1956 v 2 Sheets-Sheet 1 INVENTOR May 14, 1940- c. sAuzEDDE 2,200,305

PISTON SEAL med oct. so. 195s y 2 sums-snm -2 Cham/e Saajec/de,

ATTORNE`YS Patented May 14, 1940 aztecas PISTON SEAL omas sauzeaae, Detroit, Mich., assignmto netroit Hydrostatc Brake Corporation, Detroit, Mich., a corporation of Michigan Application October 30, 1936, Serial No. 198,351 y 5 Claims.

This invention relates to means for sealing chambers in which reciprocating elements are mounted to be moved in response to fluid pressure in the chambers, or wherein the elements 5 are to be moved by pressure means external to the chambers to place pressure on duid in the chambers in which they are mounted. It refers more particularly to hydrostatic brake systems wherein pistons movably received in chambers 10 and connected to'brake shoesv are moved with respect to their chambers by iiuid under pressure.

The primary object of the present invention is to provide a' sealing means, between a piston head and the wall of a cylindrical chamber in W which it operates in response to fluid pressure, which is' positively non-leakable and which is designed to embody high wear resisting properties. The sealing means is in the form of an open-ended cylinder and is formed of elastic man terial such as rubber, and the cylindrical rubber body or sleeve has an annular metallic reinforc- `ing surface bonded to each end thereof. For example, if the sleeve is formed of rubber itmay be vulcanized to the annular reinforcing memg5 bers. In assembling the seal in a brake of the hydrostaticy type one of the metal reinforcing members is clamped tothe wall of the cylinder and the other reinforcing member is clamped to the wall' of the piston' which operates in the 3.0 cylinder. This manner of clamping the annular reinforcements to the cylinder wall and piston head provides for a metal'to metal contact and permits the clamping parts to be tightened into such firm engagement that leakage of fluid past 5 the piston is positively prevented. This metal to metal contact is also advantageous in 'that it permits sealing elements of the deformable, soft metalv type to be interposed between the clamped parts to enhance the sealing action and render 50 inforcements are clamped to the stationary body or spider which is-designed to support the brake shoes while the other ends of the sleeves are surface bonded directly tothe element which moves in response to the fluid pressure. The sleeves are made .of a length providing suilicient material to. permit the'necessary stretching action without damage to the seals and the space resulting from elongation oi the seals in this manner is filled with a separate annular filler. The actual amount of space which is. nlled with e fluid when the brakes are inoperative is there fore comparatively small.

With the above and other ends in view theinvention consists in matters hereinafter. more particularly set forth with reference to the aci@ companying drawings, in which:

Figure 1 is a vertical section;

Fig. 2A is a vertical section taken on a plane transverse to Fig. 1;

Fig. 3 is a vertical sectionof a modined brake Bti construction; o v

Fig. 4 is a view taken on the line -i of Fig. 3, and

Fig. 5 is a section of another form of seal. Like characters of reference are employed m throughout to designate corresponding parts.

'I'he numeral i designates a fragment of aspider such as ordinarily provides the support Awith the spider are two guide arms 2 between which a. bridge member 3, supporting brake shoes 4, is slidable radially. Between the arms 2 the a@ spider is formed vwith a cylindrical projection 5 with its axis extending radially. At its'outer end the cylindrical projection t has a 4co-axial, internally threaded, annular formation t, the A outer diameter of the annular formation t being 35 less than the diameter of the projection S'Whereby to form a shoulder l. The face of the shoulder 1 is formed in a plane normal to the. axis of the annular formation 6 and is machined smooth.

A cylindrical body or wsleeve 8, formed of elastic material such as rubber, has an annular metallic reinforcement 9 the surface of which being bondedto the lower end of 8, the reinforcement being internally disposed with respect to the end of the u sleeve and having serrations on its external surface for increasing the tenacity of the surface bonding. The end of the sleeve may be vulcanized to the reinforcement 9,A for example, or w it maybe secured thereto by suitable adhesives.

At its other end the sleeve 8 has an annular metallic reinforcement I0 the surface of which being bonded thereto, externally thereof, the inner surface of the reinforcement I0 being `prou vided with serrations to increase the efficiency of ing element II the contacting surfaces of the shoulder 1, annular member 9 and shoulder I2 maybe brought into such firm engagement that passage of fluid therebetween is impossible.

Loosely received between the arms '2 is an element I3 having a cylindrical formation I4 rdisposed within the other end of the sleeve 8. The

upper end of the element I3 supports the bridge member 3 and this end is further provided with an externally screw-threaded portion I5 and a shoulder I6. Ahollow cylindrical body I1, formed with an internal shoulder I8, is screwthreaded onto the screwthreaded portion I5 and the annular reinforcement II) is clamped between the shoulders I6 and I8 thereby. A deformable seal I 9, formed of aluminum for example, is interposed between the annular reinforcement I0 and the shoulder I6. The hollow cylindrical body I1 encloses the elastic sleeve 8 and its lower end nds bearing on the cylindrical projection 5.

The -spider I is provided with passages 20 which communicate with a port y2| extending through the clamping element II and serve to convey fluid under pressure to the space between the elements II and I3. When fluid under pressure is so introduced to this space the element I3 moves outwardly radially with respect to the spider and engages the bridge member,3 to force the brake shoes 4 outwardly. During such movement of the'elernent I3 the elastic sleeve 8 is stretched but is prevented from expanding radially of itself by the confining surfaces of the cylindrical body I1. The two elements II and I3 are maintained in co-axial alignment during such movement by engagement of the lower end of the hollow cylindricalv body I1 with the cylindrical projection 5.

Referring to Figs, 3 and 4 there is illustrated a stationary spider 30 having a radially projecting shank 3I with guide portions 32. Slidably received upon the guide surfaces 32 is a cross member 33 which supports a pair ofbrake shoes 34, one of which is shown in Fig. 3. At the base of the shank 3l is provided a shoulder 35, and a cylindrical retainer 36 which is secured upon the screwthreaded portion 31 of the shank clamps an annular metallic reinforcement 38 against the shoulder 35. `An elastic seal 39 has one end thereof surface bonded to the annular reinforcement 38 and its other end surface bonded to an annular projection 40 on a movable element 4I.' ,Surrounding the base of the shank A3| is an annular formation 42 screwthreadedly receiving la retainer 43 which clamps an annular metallic reinforcement 44 against the shoulder 35. One end of an elastic sleeve 45 is surface bonded to the inner surface of the annular reinforcement 44 and its other end is surface bonded to the annular projection 40 on-the movable element 4I.

The two sleeves 39 and 45 are thus concentrically disposed and the space therebetween constitutes a fluid pressure chamber. The spider 30 is provided with passages 46 for` conveying is mounted-between the two sleeves 39 and 45 tov occupy a major portion of the space therebetween to reduce the amount of uid necessary to f ll such space. v

When fluid under pressure is supplied through the .passages 46 to the pressure chamber formed y as above described it acts upon thev ller 41 and the annular projection 40 to move the movable element 4I outwardly with respect to the shank 3 I. During such movement the movable element engages the cross member 33 vand forces the shoes 34 outwardly for contact with a brake drum. The'usual springs, not shown, are used to retract the shoes 'and to movethe cross member 33 and movable element 4I back to the position shown in Fig. 3.

In Fig, 5, there is shown a modified seal adapted for assembly in a brake construction such as shown in Fig. 3.- In this form the seal comprises inner and outer annular walls-50 and 5I respectively, the two walls being of different diameters whereby a space 52 is provided therebetween.

,The space between the two walls 50 and 5I is closed at one end by an integral annular wall 53, preferably having a comparatively hard surface portion as indicated at 54. Surface bonded internally to theopen end' of the wall 50 is an annular metallic reinforcement 55 and surface bonded externally to the youter wall 5I is an annular metallic reinforcement 56. v

In assembling the seal shown in Fig. 5, in a brake such as shown in Fig. 3, the two reinforcements 55 and 56 are clamped against the shoulder 35 by retainers such as shown at 36 and 43 respectively.

Although a-specicembodiment of the invention has been illustrated and described it will be understood that various changes may be made within the scope of the appended claims Without departing from the spirit of the invention, and such changes are contemplated.

What I claim is:

1. In a hydrostatic brake, a stationary body, an element movably mounted on said body and guided thereby for movement with respect thereto, a pair of concentric elastic sleeves having a space therebetween providing a fluid pressure chamber, said elastic sleeves each having one end secured to said stationary body and one end secured to said movable element, and means for conveying fluid under pressure to said pressure chamber.

2. In a-hydrostatic brake, a stationary body, an element movably mounted on said body and guidedlthereby for movement with respect thereto, a pair of concentric elastic sleeves having the space therebetween providing a pressure chamber, said movable element having an annular projection extending between said sleeves at -one end thereof and having said ends of said 'sleeves surface bonded thereto, means securing the other ends of said sleeves to said stationary body,

and .means for conveying fluid to said pressure chamber. t

3. In a hydrostatic brake, a stationary body, an element movably mounted on said body and guided thereby for movement with respect thereto, a pair of concentric elastic sleeves having the space therebetween providing a pressure chamber, said movable element having an annular projection extending between said sleeves at one end thereof and having said ends of said sleeves surface bonded thereto, annular metallic reinforcements securedl to the other ends' of said sleeves, means for clamping said reinforcements to said stationary body, and means for conveying y space therebetween providing a pressure chamber,A said movable element having an annular projection extending between said sleeves at one end thereof and having said ends of said sleeves surface bonded thereto, annular metallic rein' forcements secured to the other ends of said sleeves, the reinforcement on' the outer sleeve being externally disposed and the reinforcement on the inner sleeve being internally disposed,

means clamping said reinforcements to said stationary body, and means for conveying iiuid under pressure to said pressure chamber.

5. In a hydrostatic brake, a stationary support,

:an annular fluid chamber formw in said support, means for conveying uid under pressure to said chamber, means movable responsive to the fluid pressure in said chamber for operating `the brake, sealing means arranged concentrically along the opposite walls of said chamber for 10A sealing the uid therebetween, and a pair of an.- nular metallic members reinforcing said sealing means and anchoring same to said support and arranged one within the area defined by the inner sealing means and the other without the area 15 defined by the outer sealing means.

. CLAUDE SAUZEDDE. 

